Electrical musical instrument



N V- 2 9 I J. R. KAPPEL 2,960,899

ELECTRICAL MUSICAL INSTRUMENT Filed Feb. 1, 1956 4 Sheets-Sheet 1 4 Sheets-Sheet 2 Filed Feb. 1, 1956 Nov. 22, 1960 J. R. KAPPEL 2,960,899 ELECTRICAL MUSICAL INSTRUMENT Filed Feb. 1, 1956 4 Sheets-Sheet I5 POWER sa pz. Y

JOSEPH A? mf .42

United States Patent 2,960,899 Patented Nov. 22, 1960 ELECTRICAL MUSECAL INSTRUMENT Joseph R. Kappel, San Rafael, Calif. (151 Summit Drive, Corte Madera, Calif.)

Filed Feb. 1, 1956, Ser. No. 562,861

19 Claims. (Cl. 84-1.18)

The present invention relates to an improved electrical musical instrument having a keyboard such as a piano or the like and including recorded notes of the musical scale over a desired range which are individually and in combination reproduced at the direction of one operating the keyboard. Sounds other than notes of the scale may also be recorded and applied to the instrument for subsequent reproduction thereon, however, in the following description musical reproduction shall be described as a preferred embodiment of the invention.

Although numerous devices have been developed as electrical musical instruments a general difiiculty therewith has been the required complexity thereof and the necessary precision components. This situation has resulted in devices of this general type being expensive to manufacture and maintain, requiring undue maintenance for good performance, being heavy and bulky, and having very little flexibility in operation.

The present invention provides a musical instrument with all of the desirable features of similar known devices and having additional advantage in being quite simple in construction. Also the instrument of this invention is quite compact and may in fact be produced as a portable unit while at the same time not including a multitude of precision elements as is often associated with reductions in size without loss of quality.

It is an object of the present invention to provide an electrical musical instrument of electrical and mechanical simplicity with a high degree of operational flexibility.

It is another object of the present invention to provide an electrical musical instrument that produces chords without structural complications over the production of single tones.

It is a further object of the present invention to pro vide an electrical musical instrument that is portable.

It is yet another object of the present invention to provide an electrical musical instrument that has a keyboard remote from the sound reproduction apparatus.

It is a still further object of "the present invention to provide an electrical musical instrument adapted for battery operation.

It is another object of the present invention to provide an electrical musical instrument with almost unlimited audio frequency response.

it is still another object of the present invention to provide an electrical musical instrument that provides high quality sound reproduction with standard keyboard operation without a plurality of precision components.

It is a further object of the present invention to provide an electrical musical instrument that is adapted for operation with conventional amplifiers for connection to existing devices such as radios and television receivers.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following description of the preferred form of the invention which is illustrated in the drawings accompanying and forming part of the specification. It is to be understood, however, that variations in the showing made by the said drawings and description may be adopted within the scope of the invention as set forth in the claims.

The invention is illustrated in the accompanying drawings wherein:

Figure 1 is a side elevation partially in section of one embodiment of the invention.

Figure 2 is a sectional view taken at 2-2 of Figure 1.

Figure 3 is a sectional view taken at 33 of Figure 1 on an enlarged scale.

Figure 4 is a sectional view taken at 44 of Figure 1.

Figure 5 is a partial exploded perspective view of the shutter mechanism.

Figure 6 is an electrical diagram of the instrument of Figure 1.

Figure 7 is a vertical center sectional view of another embodiment of the invention.

Figure 8 is an alternative light control means shown in side elevation.

Figure 9 is a sectional view taken at 9-9 of Figure 8.

The invention generally includes a single elongated source of light which is separated from a single phototube by moving strips of film having thereon separate tones, notes, or other sounds recorded. Light from the source is controllably admitted to fall upon the tube through selected portions of the film by a pluralitv of individually operable shutters electrically controlled from a keyboard having individual keys corresponding to separate shutters. As in conventional sound film practice the film is moved at a constant speed relative to the light source and in this case also to the phototube.

Considering now the structural details of a preferred embodiment of the invention and referring to Figures 1-4 of the drawing, there is provided a rigid open base 11 upon the top of which are disposed in spaced opposing relationship a pair of upstanding end supports 12 and 13. The sup ort 12 carries a fixed axle stub 14 while the support 13 carries a fixed hollow shaft 16 with the axle stub 14- and ho low shaft directed toward each other on a common axis. A drum 17 formed as a hollow cvlinder of trans arent material such as a plastic is rotatably mounted between the end supports 12 and 13 by means of the axle stub and hollow shaft extending through end walls 18 and 19 of the drum. Suitable hearin s in the end walls 18 and 19 about the axle stub and hollow shaft p ovide for free rotation of the drum and shoulders may be formed about the axle stub and hollow shaft for fixing the drum against longitudinal displacement. A drive wheel 21 is secured to one end of the drum as about the hollow shaft and is afl'ixed to the drum as by screws 22. A motor 23 is mounted upon the base 11 adiacent the drum and is adapted to rotate the drive wheel 21 and d um bv a wheel or gear 24 joined to the motor rotor and eng ing the drive wheel in peripheral c tact therewith. The motor 23 is a constant s eed device such as a svnchronous motor so that the drum is rotated at a constant rate and the motor is adapted for connection across a power supplv for energization by motor leads 26 and through a suitable switch.

The c lindrical drum 17 is formed of a transparent material for transmitting light radially therethrough and there is dis osed interiorly of the drum an elongated phototube 31 for recei ing and utilizing light controllably transmitted through the drum. The phototube mav be mounted axia l of the drum in a socket 32 fixed within the hollow shaft 16 as by a rubber shock mounting 33 and the opposite tube end may be supported by a resilient member 34 carried on the inner end of the axle stub 1d. The tube 31 is covered over the entire length thereof by a light opaque shield 36 which has a narrow slit 37 therein extending along the length of the tube at the bottom thereof adjacent the base 11, as best seen in Figure 4. Adjacent the end support 13 carrying the tube socket 32 is disposed a preamplifier 38 mounted upon a bracket 39 secured to the base 11 and to the end sup port 13. The phototube 31 and preamplifier 38 are connected together and to an input terminal 41 while the preamplifier 38 is connected to an output jack 4?. adapted for connection to any convenient audio amplifier and speaker as may be found in conventional radio and television sets or which may be integrally provided as a portion of the electrical musical instrument of the present invention.

With regard to the control of light applied to the rotating drum 17 there is provided atop the base beneath the drum and in axial alignment therewith an elongated rectangular head 46. As shown in Figure 3, a pair of angle brackets 47 disposed one on each side of the head 46 secure the head in place as by screws into the head and bolts through the base while a top wall of the base is apertured beneath the head so that the head is suspended over the opening therein. The head 46 is formed of a light opaque material such as a light metal and is provided with a cylindrical longitudinal bore 49 within the upper half of which is disposed a semi-cylindrical lens 51. A pair of short semi-cylindrical lens keepers 52 are disposed one at each end of the head bore beneath the lens 51 and secured in position by screws 53 through the bore for supporting the lens and maintaining same fixed in position at the top of the bore. A narrow slot 54 is formed longitudinally of the head beneath same and extending into the bore for admitting light to the underside of the lens 51.

Light is provided by lighting means such as a neon tube 56 mounted in a light housing 57 below the head by means of a hollow rectangular support box 58. Vent holes may be provided in the light housing 57 and the box 58 which is secured in light-tight relationship to the head and to the housing is itself light tight to comprise a light pipe or conduit to the under side of the head. The light housing may also have light collimating plates 59 at the top thereof to define a light slit at the bottom of the box Tube mounting brackets 61 within the housing :37 provide for tube support and electrical energizaticn with one bracket serving as a tube socket connected to an electrical terminal 62 exteriorly of the housing 57.

Light is admitted to the exterior surface of the drum 17 from the light source 56 through the head 46 in a controlled manner and to this end there are provided a plurality of shutters 66 in the head above the lens :31 therein. Each of the shutters 66 are alike and considering one, as illustrated in Figures 3 and 5, same will be seen to include a plunger 67 formed of a magnetic material and disposed in a horizontal bore 68 in the head above the lens 51. The shutter bore 68 extends slightly more than halfway through the head and intersects a vertical light beam aperture 69 extending from atop the head downward into the large longitudinal head bore 49 at the lateral center of the head. The plunger 67 slidably engages the head at the plunger bore 68 and closely fits same. Plunger actuation is accomplished by a solenoid 71 disposed about a coil frame 72 having a central cylinder 73 in which the plunger is adapted to slide. The coil frame 72 is mounted upon a plate 74 extending longitudinally of the head and mounted at a spaced distance therefrom as by screws 76 extending through spacers 77, as shown in Figure 5. A spring 78 about the plunger 67 is compressed between the plate 74 and a spring keeper 79 affixed to the plunger so as to urge the plunger into the bore 68 whereby the plunger normally closes the vertical light aperture 69 in the head. By this construction light is normally not passed by the shutter upward through the head as the plunger is under spring pressure to maintain a maximum inserted position. Retraction of the plunger to open the shutter is accomplished by energizing the solenoi 71 whereby the magnetic lines of force established thereby rapidly draw the plunger more fully into the solenoid 71 and out of the head sufficiently to open the vertical light aperture 69 in the head.

Each of the shutter solenoids are separately wired as through a cable 81 to individual keys 82 of a keyboard 83 shown diagrammatically in Figure 6, and which may be positioned remotely from the sound reproduction apparatus. The individual shutters may be offset as shown in Figures 1 and 5 to allow placement of a maximum number along the head. Additionally a further bank of shutters (not illustrated) may be mounted on the opposite side of the head in offset relation to the bank illustrated to provide additional keys.

Sound is produced by the instrument by passing light beams through selected strips of sound film 84 secured about the drum, as shown in part in Figure 1. These strips may be made in a conventional recording manner from such as an organ or whatever instrument is desired. The strips are then secured about the drum immediately next to each other and a single tone or note is preferably recorded on each strip. Alternatively, the exterior drum surface may be sensitized and the sound recording strips photographically applied directly thereon. The film strips 84 are oriented on the drum to each be aligned directly above a vertical light aperture 69 of one shutter so that actuation of any one shutter passes light through a single film strip to the phototube 31. The strips 84 are quite narrow and may be very closely mounted as a very sharp light beam results from the above described light system. In this respect note that a very sharply focused beam of light is obtained with the cylindrical lens and narrow apertures and there is produced a gradual taper to the focal point so that placement of the film directly at the focal point is not critical, consequently the required precision of the elements of the instrument is not great.

Inasmuch as the instrument is electrically operated and responsive there is separately illustrated in Figure 6 a composite electrical diagram and including a power supply 91 connected across the primary winding of a transformer 92 through a switch 93. A low voltage secondary winding 94 of the transformer supplies energy for actuation of the shutters and has one end grounded with the other end connected to terminals 96 at each one of the keys 82 of the keyboard 83. The keys 82 are each switches and the two keys shown by way of example each have another terminal 97 which is connected to the transformer terminal upon depression of the key, the keys being spring loaded to normally remain raised with the switches thereof open. The key terminals 97 are connected to one end of the respective solenoids 71, each of which has the other end grounded whereby depression of the key 82 energizes its solenoid 71, with a ground return circuit being employed. Each key and the solenoid associated therewith are connected in series across the transformer winding 94 and the key-solenoid combinations are connected in parallel with each other. The drive motor 23 is energized through a starting switch 93 from a tap on another secondary winding 99 of the transformer and developing a'greater voltage than the aforementioned winding 94. The light source 56, herein taken as a neon tube, may be energized from the same tap on the secondary winding 99 through a conventional multivibrator 101, operating for example at 20 to 30 kilocycles, and connected at the terminal 62 to one end of the tube 56 which has the other end thereof grounded.

The phototube 31 has the plate electrode thereof connected to an intermediate voltage terminal of a rectifier and filter unit 102 that is in turn connected across the transformer secondary winding 99. The photo-tube cathode is connected to the preamplifier wherein it is grounded through a resistor 163. The preamplifier includes a hi mu dual triode vacuum tube 104 with the input from the phototube connected to the control electrode of the first section and the cathode thereof grounded aceosao through a resistor 106 and capacitively coupled via a. capacitor 107 to the control electrode of the second section. The first section of the tube 104 will be seen to comprise a cathode follower and the second section is connected as a straight amplifier with the cathode grounded and the grid grounded through a resistor 108. The two plate electrodes are coupled by a resistor 109 and the first plate is connected to a relatively high voltage terminal of the rectifier while the second plate is capacitively coupled to the output terminal 42. A conventional amplifier and speaker 111 is connected to the output terminal 42. The described preamplifier circuit has been found particularly Well adapted for use with a phototube such as a 918 gas phototube and note in this respect that maximum sensitivity of this tube lies in the red and infra red spectrum, about 8000 Angstrom units, so that the use of a neon light source, as herein shown, is advantageous for maximum emission lies in this band. Other types of phototubes and light sources have proven quite satisfactory.

Another embodiment of the invention is illustrated in Figure 7 and as many of the components are the same as described above in connection with Figures 1-6 like elements are given the same numbers in Figure 7 as in the other figures. In this embodiment the cylindrical drum is replaced by a rotatable turntable 201 formed of a transparent material such as plastic and horizontally mounted at the center thereof upon a vertical shaft 202. An annular metal member 203 may be employed to join the turntable and shaft with the shaft remaining below the level of the turntable to form a central depression 204 at the center of the turntable. The shaft 202 is mounted for rotation in upper and lower bearings 206 maintained in position by a vertical cylinder 20-7 rigidly afiixed to a base plate 208 as by bolts through a flange about the lower end of the cylinder and through the base plate. The turntable 201 is rotated by means of a motor 23 mounted upon the base plate and driving the turntable as through a friction wheel 24 mounted on the motor shaft and engaging the turntable periphery. Motor leads 26 are adapted for connection as in Figure 6 for energizing the motor.

Controlled light beams are directed through the turntable 201 from one or more light units 209 mounted directly above turntable. Each light unit 209 is substantially the same as that previously described and shown in Figures l and 3 except that same is inverted. Thus at the bottom of the light unit directly above the turntable is a head 46 having a plurality of spaced electrically controlled and operated shutters 66 therein with a light source displaced above same and connected thereto by a light-tight box 58. The light unit is mounted upon the base plate by any suitable means such as a standard 211. Light beams passing through the turntable are intercepted by a phototube 31 positioned directly below the light unit and phototube signals are amplified in a preamplifier 38 mounted upon the base plate 208, all as previously described.

One of the advantages of the present embodiment lies in the fact that the sound films are readily interchangeable and this is accomplished by placing film strips 212 upon the surface of a transparent disk 213 adapted to rest upon the turntable and to rotate therewith. The film strips herein employed extend in circles upon the disk surface and the disk is provided with a central transverse aperture adapted to align with the depression 204 in the turntable when the disk is aligned thereon. A vertically mounted plunger 214 is disposed directly above the turntable depression 204 with a solenoid 216 thereabout and if desired a spring 217 urging the plunger downward. The solenoid 216 is adapted for connection rom a lead 218 through a release switch (not shown) across a power supply (also not shown), as for example across the winding 94 in Figure 6. The release switch is conventionally operated so as to energize the solenoid whereby the plunger is raised out of the disk and turntable depression so that the disk may he slid from the table. Deenergization of the solenoid 216 allows the plunger 214 to fall into the turntable depression through the central disk aperture, thereby locking the disk in position as the plunger closely mates with the disk aperture, and consequently causing the disk to rotate with the turntable.

Additional light units and light receiving units may be spaced circumferentially about the turntable with a consequent multiplication of the number of shutters and keys without crowding the shutters. Operation and energization of this embodiment follows the prior description and electrical diagram of the previously described embodiment.

The alternative head and shutter arrangement shown in Figures 8 and 9 is particularly advantageous in that very close spacing of shutters is possible without crowding, Figure 8 being substantially full scale with eight shutters per inch. Also, problems of shutter alignment are obviated by direct attachment of head and solenoids Without intervening spaces. The head 301 formed of an opaque material, such as brass for example, has a longitudinal bore 302 therein with a transverse slot 303 between the bore and the back side of the head. A light source, not shown, is adapted for connection to the back side of the head in light-tight relation thereto for supplying light through the slot 303 into the bore 302 and an elongated semi-cylindrical lens 304 is mounted within the bore with the convex portion thereof mating with the front side of the bore opposite the slot. A pair of lens keepers 306 may be mounted behind the lens with one at each end thereof for fixing the lens 304 in position. A plurality of small horizontal light apertures 307 are formed through the front of the head in a line longitudinally thereof and communicating with the bore 302. These apertures 307 are individually intersected by small vertical shutter bores 308 with one bore intersecting each light aperture 307. The shutter bores 308 are aligned in two lines longitudinally of the head with alternate bores on separate lines so that the bores are staggered along the head and atop the head are disposed a plurality of shutter actuating mechanisms 309. Considering one mechanism 300 same will be seen in Figure 9 to comprise a solenoid including a hollow metal cylindrical coil holder 311 having a coil 312 wound thereabout with metal coil end piece 313 and 314 affixed to the coil holder 311. A cylindrical plunger 316 formed of a magnetic material is slidably disposed within the coil holder 312 and has a tapered lower end for reducing initial light impact on the light sensitive device. The shutter actuating mechanism is mounted directly above a vertical shutter bore 308 and the upper portion of this bore may be enlarged to receive the lower end of the coil holder 311 in a pressed fit while the plunger fits the smaller bore diameter in slidable relation thereto. Beneath the head is disposed a plate 317 holding a soft layer of material such as a felt pad 318 and attached to the head by machine screws 319'. Atop the solenoids is a second felt pad 321 with a strap 322 extending across same and downward into attachment with the head at the ends of the solenoid array as by machine screws 323.

It will be appreciated that the plungers 316 of the solenoids 309 are normally resting on the pad 318 fully engaged with the bores 308 and in closing relation to the light apertures 307 by the force of gravity. It is required only that the plungers be disposed substantially vertical for them to rapidly and satisfactorily return to fully inserted position in the bores 300 following actuation and tests show displacement of the plunger as much as 35 degrees from vertical, as by head tilting, does not adversely affect plunger operation.

Actuation of the plungers 316 is accomplished by ener gizing the solenoid windings 312 and simplified wiring is accomplished by grounding the lower end of the wind ing to the coil holder 311 and attaching a lead 324- to the top end of the winding for connection to a grounded power supply. A terminal strip 326 may be mounted upon insulating spacers 327 upon the head 301 as by machine screws or bolts 328 with the solenoid leads 324 attached to lugs 32 along one side of the strips and leads 331 extending from lugs 332 along the other side of the strip and individually connected to the solenoid lugs. The leads 331 are connected individually to switches in parallel on a keyboard to a power supply for control of the individual solenoids in the manner previously set forth.

What is claimed is:

1. An electrical musical instrument comprising a plurality of aligned electrically operated shutters having tapered cross sections, a plurality of key switches connected one in series with each of said shutters, power supply means connected across said shutter-switch combinations in parallel whereby switch actuation moves a connected shutter to present an effective shutter area of decreasing size, a light source directing light upon one side of said shutters, light responsive means producing electrical signals responsive to incident light, a plurality of strips of sound film with each depicting a separate musical note and disposed adjacent one another, and means moving said film strips past said shutters at a constant controlled speed with each strip aligned with a shutter whereby key actuation causes said light sensitive means to be actuated in accordance with particular film strips for producing electrical signals proportional to particular musical notes.

2. An electrical instrument as claimed in claim 1 further defined by the means moving said film strips including a transparent drum carrying said strips and driven by a constant speed motor.

3. An electrical instrument as claimed in claim 1 further defined by said film strips being mounted concentrically upon a transparent disk and the means moving said film strips comprising a turntable driven by a constant speed motor and carrying said disk in removable relation.

4. An electrical musical instrument comprising a head having a plurality of small light passages therethrough, a light source, a lens in said head focusing light from said source through said passages therein, a plurality of shutters having tapered ends individually closing the light passages in said head and including electrically responsive actuating means for separately opening same to graduate light transmission therethrough, a keyboard having a plurality of key switches individually connected in series with separate shutter actuating means, power supply means electrically connected in parallel with said shutter key switch combinations, means carrying a plurality of sound film strips of difierent notes for moving same at a constant speed past said head with each strip aligned with a separate shutter, and light responsive means disposed on the opposite side of said film strips from said head and producing electrical signals proportional to incident light.

5. An electrical musical instnlment as defined in claim 4 further characterized by the means carrying said film strips comprising a transparent drum mounted for rotation and having said strips secured circumferentially thereabout in axial displacement.

6. An electrical musical instrument comprising a transparent turntable, means rotating said turntable at constant speed, a plurality of aligned shutters mounted adjacent said turntable with said shutters having a normally' closed position and electrically responsive actuating means, a light source directing light through said shutters, a plurality of switches connected separately to individual shutter actuating means and adapted to energize same from a power supply, light responsive means on the opposite side of said turntable from said shutters and producing electrical signals in response to incident light, and a transparent disk having sound film strips mounted concentrically thereon and adapted for removable disposition upon said turntable for rotation therewith and aligning said film strips separately with individual shutters whereby switch actuation controls output of said light responsive means.

7. An electrical instrument as defined in claim 6 further characterized by an elongated cylindrical lens mounted intermediate said light source and said shutters for focusing light through the latter upon said film strips and means collimating the light whereby elongated arrows of light reach said film through open shutters.

8. An electrical musical instrument comprising an opaque head having a plurality of parallel light passages therethrough and a plurality of transverse shutter openings individually intersecting said light passages, a plurality of solenoid-actuated spring loaded plungers disposed one in each of said transverse head openings in closing relation to intersected light passages, a light source, a lens focusing light from said source through said light passages on to a plane, means carrying a plurality of sound film strips of separate musical notes at a constant speed past said head with individual strips aligned with separate shutters in said plane, light responsive means on the opposite side of said plane from said light source and producing electrical signals responsive to incident light, amplifier and speaker means connected to said light responsive means for reproducing notes from said film strips, and a keyboard with a plurality of key switches each connected to one shutter and to a power of supply for actuating said shutters.

9. An electrical musical instrument as claimed in claim 8 further defined by the means carrying said film strips comprising a transparent rotatable drum surrounding said light sensitive means.

10. An electrical musical instrument as claimed in claim 8 further defined by the means carrying said film strips comprising a transparent disk removably mounted upon a rotatable turntable.

11. An electrical musical instrument comprising a transparent turntable rotatable at constant speed, a plurality of electrically actuated shutters disposed adjacent said turntable and aligned radially thereof, a light source directed through said shutters to focus above the upper surface of said turntable, light responsive means producing electrical signals responsive to incident light disposed on the opposite side of said turntable from said light source, and a transparent disk having concentric sound film strips thereon of diiierent musical notes adapted for removable disposition on said turntable to rotate therewith. g

12. An electrical musical instrument as claimed in claim 11 further defined by a solenoid-actuated plunger mounted above said turntable at the center thereof and having a normal position contacting a depression at the center of the turntable through a central disk aperture for locking said disk and turntable together and an actuated position raised above the turntable for disk removal. V p

13. An electrical musical instrument comprising a transparent element rotatable at a constant speed, a plurality of sound film track upon said transparent element, a light source directing light through said rotatable element, a plurality of shutters individually aligned with separate film tracks and controlling light incident thereon, light responsive means disposed on the opposite side of said film tracks from said light source, and a single elongated lens focusing light from said source at said film tracks.

14. An electrical musical instrument as claimed in claim 13 further defined by said light source comprising a single elongated source and said light responsive means comprising a single elongated device producing electrical signals proportional to incident light.

15. An electrical musical instrument comprising a rotatable transparent film carrier having a plurality of aligned sound tracks thereon, light responsive means mounted upon one side of said film tracks for producing electrical signals proportional to incident light transmitted through the sound tracks, a light source on the opposite side of said film tracks from said light responsive means, and a plurality of electrically actuated shutters including substantially vertically disposed plungers interposed between light source and light responsive means and controlling light to the latter.

16. An electrical musical instrument as claimed in claim 15 further defined by a light opaque head having light passages therethrough directing separate light beams upon said light responsive means in alignment with separate sound tracks, said shutters being magnetic plungers slidably disposed in substantially vertical bores intersecting the light apertures in said passage and individually surrounded by solenoids mounted directly on said head and adapted for connection in parallel across a power supply through separate switches.

17. A shutter head for an electrical musical instrument comprising a light opaque head having a longitudinal bore therein for retaining an elongated cylindrical lens and having a slot therein communicating between said bore and the back side of the head whereby light is admitted into the bore, said head defining a plurality of light apertures through the head between the bore at said lens and the front side of the head and further defining a plurality of substantially vertical bores individually intersecting separate light apertures, a plurality of solenoids mounted directly atop said head with one above each vertical bore therein, and a plurality of magnetic plungers disposed one in each vertical bore with a normal position closing the intersected light aperture and an operated position upon solenoid energization raised out of closing relation to the light aperture whereby light controllably passes therethrough.

18. An electrical musical instrument comprising means rotating film strips past a line, a light source and a light responsive means disposed on opposite sides of said line for film strip transport therebetween, an opaque block disposed intermediate said light source and light responsive means having a plurality of parallel closely spaced passages therethrough all directed between said light source and light responsive means, a single lens focusing light from said light source through said passages upon said light responsive means, a plurality of metal spring loaded tapered plungers disposed in said block to normally close each of said passages, a solenoid disposed about each of said plungers for withdrawing same against spring tension from closing relation to the passage normally closed thereby, and a plurality of keys connected to electrically energize said solenoids for selectively opening said passages to the passage of light therethrough.

19. A shutter head for an electrical musical instrument comprising an elongated opaque block having a longitudinal opening therethrough and a plurality of closely spaced parallel passages transversely therethrough intersecting said longitudinal opening, a semi cylindrical lense disposed in said longitudinal block opening for focusing light transmitted through said transverse passages, said block further defining a plurality of transverse apertures substantially normal to said passages with each aperture intersecting one passage, a plurality of solenoids mounted on said block with one aligned with each aperture therein and having plungers disposed one in each aperture with the plunger end in said apertures being tapered, and a spring engaging each of said solenoid plungers and urging same into said block for closing the passages therein whereby individual solenoid energization selectively opens separate passages through said block for light transmission therethrough.

References Cited in the file of this patent UNITED STATES PATENTS 1,848,222 Potter Mar. 8, 1932 1,937,021 Hammond Nov. 28, 1933 1,998,461 Kucker Apr. 23, 1935 2,169,842 Kannenberg Aug. 15, 1939 2,489,857 Bullian Nov. 29, 1949 

